May a college expel a student for ‘unprofessional speech’ in Facebook posts?

Eugene Volokh:

Say a student is in a professional education program at a college — law school, medical school, nursing school, business school, school of education or the like. May the college expel him from the program, on the grounds that certain speech of his is “unprofessional” and therefore casts doubt on his professional temperament and likely future behavior?

We’re not talking here about speech within a curricular assignment — a thesis, a term paper, a practicum client counseling session or even a seminar discussion in which participation is graded. Colleges have to evaluate the content of such curricular speech, though even there they may be constrained. (If I grade class participation at UCLA, for instance, I can only count it as part of the final grade, and I’m supposed to grade it in a way that’s as ideologically neutral as possible.) Rather, we’re talking about speech outside such graded discussions, often outside class and sometimes even outside school.